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Pure silica ITQ-7 zeolite of topology ISV synthesized in fluoride media possesses a 3D 12-membered-rings pore system. Originally the structure of ITQ-7 zeolite was solved and refined from a calcined sample in the highest possible space group symmetry P4 2 / mmc . This space group leads to only 5 independent silicon T sites for this structure. However, this high symmetry was not supported by solid state 29 Si MAS NMR spectroscopy. In this short communication, we show from a revised 29 Si solid state MAS NMR and Rietveld analyses, that lowering of the space group symmetry from P4 2 / mmc to P4 2 consolidates structure model and experimental data, in particular, the number of non equivalent crystallographic T sites passing from 5 to 16, is in agreement with 29 Si solid state NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: An alternative to the Evaporation Induced Self Assembly (EISA) method is described as a fast and simplified approach towards mesoporous silica films. The sol–gel process is photochemically triggered with the aid of photoacid generator (PAG), thereby making mesostructuration independent of film deposition conditions, solvent evaporation and complex chemistry associated with a silica sol. The developed solvent-free synthesis uses non-ionic poly(ethylene oxide)-based surfactants and polydimethoxysiloxane, affording after UV irradiation a film with a wormhole porous framework, and a uniform pore size distribution. The disordered mesostructure was characterized by X-ray diffraction, N2 adsorption, 29Si solid-state NMR and transmission electron microscopy. [Copyright &y& Elsevier]